280Z Fuel Lines

[karlb]

Gentlemen

I am replacing the rubber fuel lines on a stock 77 280Z, in an attempt to fix an apparent vapor lock condition. The fuel pump is operating and when cool pumps quite well. I have several questions. These are:

1. Is regular fuel line (not for FI) appropriate for the supply line between the fuel tank and the fuel pump?

2. Is there a simple way to check for proper operation of the fuel damper? If it is not operating properly, how would its failure affect the operation of the vehicle?

3. Is there a simple way to check for the proper operation of the fuel pressure regulator (on the fuel rail)? If is not operating properly, how would its failure affect the operation of the vehicle.

Thanks in advance for your advice and assistance

Karlb

[sblake01]

EFI doesn't vapor lock. It operates at a high enough pressure to push fuel, vapor and anything else through the sytem. Except for sediment, rust, crud, etc. I would use fuel injection rated line for any line in an EFI sytem. If the fuel damper is bad, the sound of the fuel pump will be abnormally loud. Improper fuel pressure can cause any or all of these: difficult starting, high or rough idle, misfiring, lack of power, hesisitation/stumble, surging, dieseling, and poor fuel economy. Here's a scan from the FSM:

[Arne]

Side note, on other cars I've owned, fuel pumps typically fail when warm, and often work fine when cold. You may simply be in the early stages of pump failure.

FWIW.

[sblake01]

Good point, Arne. I was addressing his three questions and skipped over the fuel pump. If the fuel pump is malfunctioning and not producing enough pressure that could produce symptoms similar to vapor lock. But technically speaking, on an EFI car there's no such thing as vapor lock. Someone will always bring up the ZX cooling fan an contend that it was an attempt to cure vapor lock but in actuality the fan was part of the emission control system supposedly designed to lower emissions by cooling the fuel mixture. Must not have realy been too big a deal. They only put it on the ZX's. 810's and Maximas didn't have them.

[karlb]

Gentlemen

Thanks for your expert advice.

The fuel pump is about 2 years old. It seems to work fine. The fuel filter is a year old.

The car hesitates as if it were running out of fuel after about 40 miles, then it quits This occurs on hot days with the A/C running. Allowing the car to cool down for about an hour-it restarts easily and runs another 40 miles.

While still hot, just after quiting, removing the hose between the fuel filter and the fuel rail input line, results in a release of presurized air, but almost no fuel. If FI cars don't vapor lock, is there another explanation for the air besides worn fuel lines?

Thanks in advance for your assistance

Karlb

[sblake01]

I run my cars (the 810 and the Z) in hot weather with the AC on all the time. It was 101 degrees today. I have never expericnced what you're describing in either car. Both of my pumps are older than that. I'd suggest the fuel pressure check. If the pump is working properly but the regulator is bad in such a way that the pressure is low, it could cause that problem.

[76Datsun280z]

I had something similar to this happen early this year, only it would happen when I'd go to start the car after it was warm, not when I was driving it. Stephen suggested to me that I take the carbon canister out and clean the filter out with a solvent and spray carb. cleaner into the nipples of the canister and to blow them out with low air. Guess what, it's never happened again, even on these really hot days this summer. Not to say this is your problem, but it's worth a try if you're out of ideas.

[KDMatt]

The car hesitates as if it were running out of fuel after about 40 miles, then it quits This occurs on hot days with the A/C running. Allowing the car to cool down for about an hour-it restarts easily and runs another 40 miles.

While still hot, just after quiting, removing the hose between the fuel filter and the fuel rail input line, results in a release of presurized air, but almost no fuel. If FI cars don't vapor lock, is there another explanation for the air besides worn fuel lines?

Yes there is.

Have you had your fuel tank cleaned lately? (Or rather, have you had its cleanliness examined?) What it sounds like to me is that there is sediment or other crud at the bottom of the tank that's getting sucked up into the screen at the input of the fuel pump and this is causing blockage... blockage that goes away after the car's been shut off and the junk is no longer subject to suction from the pump.

If this is truly what it is, and you can only go about 40 miles before it dies, I would imagine it's pretty serious but this seems to be a relatively common issue.

[hansen77]

Karlb

It looks like most of your questions have been answered but I thought Id give you this web address to go to, there is a book you can print off or just look through that explains alot about the efi system and it also has a troubleshooting section. I found this pretty informative.

www.atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf

You will need Adobe, Hope this is helpful

[sblake01]

I get an error when I try to the link. I have that somewhere on my computer. It's more directed towards a 75-76.

[karlb]

Gentlemen

Your help has been invaluable. I have had this car since '78. This is the first bit of inconvenience.

I have ordered a fuel pressure gauge. Should be here tomorrow. Will test in the AM.

The link to the EFI book, posted by Hanson 77, doesn't seem to work. Will try going directly to the web site.

Also planning to drop the fuel tank tomorrow.

Thanks as always

Karl

Retired and "Doing nothing better every day, while making it look hard".

[karlb]

Gentlemen

Just a quick update. It was grunge everywhere: fuel rail, fuel lines and fuel tank. Its just old and not driven enough anymore.

Thanks again for all your help.

karlb

Retired and doing nothing better every day, while making it look hard